Retractors, also known as wound spreaders, serve to hold open a wound during a surgical procedure and to allow the operator free access to the surgical area.
In a typical mode of construction, retractors comprise two spreader levers (“branches”) that are connected to one another in hinged manner and are provided on one side of the hinge with spreader arms for insertion into an incision and on its other side with actuation arms for actuating the retractor. Attached to the spreader arms, as a rule, are flat-shaped spreader elements (“blades”), which can be hooked onto the borders of the incision. The two spreader levers can be pivoted and the blades can be brought to a selectable relative distance by means of a manual actuation of the actuation arms, which are usually equipped with finger insertion loops for this purpose. A releasable catching toothed connection serves to block the spreader lever in the particular spread position.
Retractors of this type are commercially available in considerable number, for instance as the Weitlaner retractor (DI 58249), and have already been copiously described in patent literature.
The disadvantage of retractors, in particular, is the fact that the blades are frequently not replaceable, so that various retractors must be kept in reserve for different uses, depending for instance on the strength of the tissue layer that is to be held back. This involves relatively high manufacturing costs. In addition, in many cases, only when the retractor is inserted in the wound is it possible to know which blades are best suited to hold the wound open. However, because retractors are usually equipped with symmetrically shaped blades, even when a retractor with blades that are basically appropriate in shape and size is inserted into a wound, an unsatisfactory result can occur if opposite sides of a wound are situated at different anatomical heights. In this case a difference in working length is required for the oppositely placed blades.
To solve this problem, German patent No 35 09 787 C2 discloses a surgical instrument for spreading the edges of a wound with blades whose gripping range or working length is adjustable. The blades each consist of two parts that can be slid with respect to one another and that can be moved into different relative positions and fixed there by a spindle mechanism. The gripping areas are displaced by manually rotating the spindle with a screwdriver.
The principal disadvantage of this surgical instrument is the two-part configuration of the blades and their coupling by a spindle mechanism, causing relatively high production costs in industrial mass manufacturing. In addition, the displacement of the working length of the blades can be achieved only with some difficulty by using a screwdriver, sometimes costing no small loss of time in the course of an operation and requiring a helping “third hand.” Owing to the use of a tool to adjust the working length of the blades and the possibility of exerting a relatively great force in the process, there is the risk that the blades can be adjusted at too great a length and that tissue can be unintentionally damaged. In addition, blades of this type are difficult to clean, because impurities can easily become lodged, in particular, in the area between the two parts of a blade and in the threads of the spindle mechanism.
Another important disadvantage of this instrument is the fact that the blades are not replaced, so that only the working length of the blades can be adjusted, without any possibility of varying the shape of the blades, in particular the number of prongs.
On the other hand, it is the object of the present invention to make available a surgical retractor by which the cited disadvantages of conventional retractors with blades with adjustable gripping range can be avoided.